This project seeks to elucidate the mechanisms by which oral sensory and perceptual experience is generated. Since objective measurement of the various aspects of oral experience is fundamental to this effort, the selection and refinement of appropriate psychophysical methods is a primary and continuing project concern. Currently, the routine assessment of taste is carried out using aqueous solutions representing each of the four basic tastes. Measures include both (detection) thresholds and judgments of intensity for taste stimuli at higher, more commonly encountered levels of strength. These methods, applied to the study of age-associate changes, have provided insights into basic mechanisms of normal chemosensory perception. Functional variation under pathologic circumstances is assessed through objective evaluations of oral sensory disturbances occurring in association with systemic disease, salivary gland dysfunction, therapeutic X-irradiation, eating disorders or as an isolated complaint. Assessments of olfactory identification as well as sensitivity to local pressure on the tongue and to variation in the temperature or the viscosity, of an oral bolus are obtained when they can contribute to an understanding of oral sensory function in relation to the complex stimuli encountered in everyday life.